KR101794876B1 - Cylindrical member made of flake graphite cast iron - Google Patents

Abstract

It has excellent mechanical strength while having practical workability and further excellent abrasion resistance and resistance to sintering. 2.85% or more to 3.35% or less, Si: 1.95% or more to 2.55% or less, Mn: 0.45% or more to 0.8% or less, P: 0.03% or more and 0.25% or less At most 0.15% of S, at most 0.15% of S, at least 0.15% of Cr, at most 0.55% of Mo, at least 0.15% of Mo and at most 0.65% of Ni, and at most 0.15% or more of 0.65% of Ni and the balance of Fe and inevitable impurities Casted graphite cast iron member.

Description

TECHNICAL FIELD [0001] The present invention relates to a cylindrical member made of graphite cast iron,

The present invention relates to a cylindrical member made of flake graphite cast iron.

A cast iron member excellent in lubricating action by graphite existing in a matrix is widely used as a member requiring wear resistance such as a cylinder liner, a brake drum, and an elevator component of an internal combustion engine (Patent Documents 1 and 2).

As the cast iron member, it has been proposed to have various compositions, textures, and properties. For example, members exemplified in Patent Documents 1 and 2 are examples of cast iron cast iron cast members.

Patent Document 1 discloses a steel sheet having a tensile strength of 250 MPa or more and a base hardness of 250 HV or more and containing 2.70% to 3.90% of C, 1.20% to 2.80% of Si, and 1.00% And the balance of Fe and inevitable impurities, and a structure in which the composition is dispersed in an area ratio of not more than 6.0% as a carbide area ratio.

Therefore, it is possible to provide a component for an elevator which is excellent in mechanical strength and machinability and can be easily manufactured at low cost.

Patent Document 2 discloses a steel sheet having a thickness of 30 mm to 350 mm and a tensile strength of 250 MPa or more and containing 2.4 to 3.6% of C, 0.8 to 2.8% of Si, 1.1 to 3.0% of Mn, % Of P, 0.01 to 0.6% of B, 0.001 to 0.2% of B, and the balance of Fe and inevitable impurities, and a composition containing carbides dispersed in an area ratio of 8% or less There has been proposed a cylinder liner for a marine engine of cast iron cast iron.

Therefore, it is possible to provide a cylinder liner for a ship engine, which is thick, has high strength, and is inundated.

Japanese Patent Laid-Open Publication No. 2014-189824 Japanese Patent Application Laid-Open No. 2014-62318

On the other hand, it is also important that the cast iron member used as a member requiring wear resistance is hard to cause the sliding contact surface to be easily removed.

In addition, when the cast iron member is required to be made lighter or thinner, it is necessary to ensure mechanical strength that satisfies such a requirement, while securing workability to such an extent that productivity is not impaired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cast member made of cast iron graphite cast iron having excellent mechanical strength and practical workability and further excellent abrasion resistance and resistance to sintering.

The above object is achieved by the present invention described below. In other words,

The cast iron graphite cast iron member according to the first aspect of the present invention is a cylindrical member of cast iron graphite cast iron, and the cast iron graphite cast iron has a mass percentage,

C: not less than 2.85% but not more than 3.35%, Si: not less than 1.95% and not more than 2.55%, Mn: not less than 0.45% and not more than 0.8%, P: not less than 0.03% and not more than 0.25%, S: not more than 0.15%, Cr: , Mo: not less than 0.15% and not more than 0.65%, Ni: not less than 0.15% and not more than 0.65%

And the balance of Fe and inevitable impurities.

The cast iron graphite cast iron cylindrical member according to the second aspect of the present invention is a cylindrical cast iron cast iron graphite cast iron member,

C: not less than 2.85% but not more than 3.35%, Si: not less than 1.95% and not more than 2.55%, Mn: not less than 0.45% and not more than 0.8%, P: not less than 0.03% and not more than 0.25%, S: not more than 0.15%, Cr: 0.15% or more and 0.65% or less of Mo, 0.15% or more and 0.65% or less of Ni, 0% or more and 0.6% or less of other elements other than C, Si, Mn, P, S, Cr, Including,

And the balance of Fe and inevitable impurities.

In an embodiment of the cast iron-made cast iron-made cylindrical member of the second invention,

And the other element is Cu, and it is preferable that Cu: 0.05% or more and 0.55% or less in mass percent.

In another embodiment of the cast iron graphite cast iron member of the first and second inventions, it is preferable that the cast iron graphite cast iron has a structure containing at least one base selected from the group consisting of pearlite and bainite.

In another embodiment of the cast iron graphite cast iron cylindrical members of the first and second inventions, it is preferable that the content of Mo in the cast graphite cast iron is 0.20% or more and 0.55% or less by mass percentage.

The other embodiments of the cast iron graphite cast iron members according to the first and second inventions are characterized in that the cast iron cast iron has a mass percentage of i) 0.20% or more and 0.55% or less of Mo in the cast graphite cast iron, and ii) And Ni is preferably 0.60% or more and 1.15% or less.

In another embodiment of the cast graphite cast iron member of the first and second inventions, the thickness of the cylindrical member is preferably 3.5 mm or less.

In another embodiment of the cast iron graphite cast iron member of the first and second inventions, the cast iron graphite cast iron has a hardness of 102 HRB or more and 112 HRB or less, a tensile strength of 300 MPa or more, and a Young's modulus of 110 GPa or more .

In another embodiment of the cast iron graphite cast iron member according to the first and second inventions, the cast iron graphite cast iron contains carbide, while in the continuous region of 0.2 mm or more in the radial direction of the cylindrical member, Is not less than 0.9% and not more than 5.0%.

It is preferable that the length of the continuous region in the radial direction of the cylindrical member is 2.7 mm or less in another embodiment of the cast graphite cast iron cylindrical member of the first and second inventions of the present invention.

The other aspect of the cast iron graphite cast iron cylindrical member according to the first and second aspects of the present invention is characterized in that any one face selected from the inner circumferential face and the outer circumferential face of the cylindrical member is provided on one end of the continuous region with respect to the radial direction of the cylindrical member .

In another embodiment of the cast iron graphite cast iron cylindrical members of the first and second inventions, the inner circumferential surface is formed on the innermost circumferential side of the continuous region with respect to the radial direction of the cylindrical member, while the inner circumferential surface is defined by the piston and the piston ring It is preferable to use a cylinder liner for an internal combustion engine.

In another embodiment of the cast graphite cast iron cylindrical member according to the first and second inventions, the inner peripheral surface is formed on the innermost side of the continuous region with respect to the radial direction of the cylindrical member, while the inner- It is preferable that the drum brake is a brake drum.

According to the present invention, it is possible to provide a cast member made of cast iron graphite cast iron which has excellent mechanical strength and practical workability and is further excellent in wear resistance and resistance to sintering.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a graph showing the relationship between the content of Mo and Ni and the matrix structure of the cast iron graphite cast iron used for the cast graphite cast iron cylindrical members of the first and second inventions of the present invention. Fig.
2 is a schematic view showing an example of a case where the cast graphite cast iron cylindrical member of the first and second inventions is used as a cylinder liner.
2 (A) is a perspective view showing an example of an internal combustion engine having a cylinder liner made of cast iron graphite cast iron members of the present embodiment, and Fig. 2
Fig. 2 (B) is a perspective view showing an example of a cylinder liner made of a cast plate made of cast iron graphite cast iron according to the present embodiment before being used in the production of an internal combustion engine,
Fig. 2C is an enlarged cross-sectional view showing an example of the cross-sectional structure between IIC and IIC in Fig. 2A.
Fig. 3 is a schematic cross-sectional view showing an example in which the cast graphite cast iron cylindrical member of the first and second inventions is used as a brake drum of an internal-type drum brake.
4 is an example of a photomicrograph (magnification: 400x magnification) of Example 11.
Fig. 5 is an example of an image (magnification: 400 times) after gray scale used for determining the carbide area ratio in Example 11. Fig.
6 is a side view of a stick-shaped test piece used for measurement of tensile strength and Young's modulus.
Fig. 7 is a schematic view of a ring-on-plate type reciprocating friction tester used for evaluating resistance to wear and abrasion.

The flaked graphite cast iron cylinder member of the first embodiment is a cylindrical member of a cast iron graphite cast iron member,

C: not less than 2.85% but not more than 3.35%, Si: not less than 1.95% nor more than 2.55%, Mn: not less than 0.45% nor more than 0.8%, P: not less than 0.03% nor more than 0.25%, S: not more than 0.15% 0.15% or more and 0.55% or less of Cr, 0.15% or more and 0.65% or less of Mo, 0.15% or more and 0.65% or less of Ni,

And the remaining portion has a composition composed of Fe and inevitable impurities.

The cast iron graphite cast iron cylindrical member of the first embodiment using the cast iron graphite cast iron having such a composition has excellent machinability while having excellent mechanical strength and further has excellent abrasion resistance and seizure resistance.

The graphite cast iron used in the cast graphite cast iron cylindrical member of the first embodiment and the cast iron graphite cast iron cylindrical member of the second embodiment to be described later (hereinafter, simply referred to as " cast iron " Composition and organization will be described in detail.

In the following description, when the matters common to both the cast graphite cast iron cylindrical member of the first embodiment and the cast iron graphite cast iron cylindrical member of the second embodiment to be described later are mentioned, Graphite cast iron-made cylindrical member or cylindrical member of the embodiment.

In addition, the content of each element represented by a percent notation means a mass percentage (wt%) unless otherwise specified.

C is an element having a function of promoting the generation of pearlite as a base organization, increasing the strength of cast iron, and improving the self-lubricating property by forming graphite graphite.

Further, C improves abrasion resistance and anti-seizure property by precipitating a carbide.

In order to obtain such an effect, the content of C is required to be 2.85% or more.

On the other hand, if the content of C is too large, the crystallization of the graphite increases and a sufficient tensile strength can not be obtained.

Therefore, the content of C is required to be 3.35% or less.

The content of C is preferably 2.90% or more and 3.20% or less.

Si is an element contributing to the crystallization of graphite in cast iron.

In order to crystallize an appropriate amount of graphite, the Si content is required to be 1.95% or more.

On the other hand, if the content of Si is too large, ferrite tends to precipitate and the strength is lowered, and a sufficient tensile strength can not be obtained.

Therefore, the content of Si is required to be 2.55% or less.

The content of Si is preferably 2.00% or more and 2.45% or less.

Mn is an element having an action to stabilize pearlite when graphite is made finer and pearlite is produced as a matrix.

In the molten iron, Mn is combined with S to form MnS, which improves the machinability of the cast iron cast iron.

In order to obtain such an effect, the content of Mn is required to be 0.45% or more.

On the other hand, when the content of Mn is too large, the graphite crystallization is disturbed and the friction characteristics are deteriorated.

Therefore, the content of Mn is required to be 0.8% or less.

P is an element contributing to wear resistance by increasing the hardness of cast iron and precipitating steadite (ternary eutectic organization of Fe ₃ P and Fe ₃ C and Fe).

In addition, when the P content is too large, a coarse staggered phase is formed to increase the aggressiveness of the counterpart member, resulting in deterioration of toughness and workability.

Therefore, the content of P is required to be 0.25% or less.

On the other hand, the lower limit of the content of P is not particularly limited, but even if P is not intentionally included, P is at least 0.03% as impurities which are unavoidable in cast iron.

Therefore, the content of P may be 0.03% or more.

The content of P is preferably 0.05% or more and 0.20% or less.

S is an element which contributes to the improvement of cutting ability of cast iron by forming MnS in combination with Mn in molten iron.

If the content of S is too large, the cast iron is broken and the desired strength can not be secured.

Therefore, the content of S is required to be 0.15% or less.

On the other hand, the lower limit of the content of S is not particularly limited, but even if S is not intentionally added, at least 0.03% of S is inevitable impurities contained in the cast iron.

The content of S is preferably 0.03% or more and 0.10% or less.

Cr is an element that strengthens the base by making the base more dense and increases the strength and hardness of the cast iron, and is effective in improving oxidation resistance.

In order to obtain such an effect, the Cr content is required to be 0.15% or more.

On the other hand, if the content of Cr is too large, toughness and processability are lowered.

Therefore, the content of Cr is required to be 0.55% or less.

The Cr content is preferably 0.25% or more and 0.55% or less.

Mo strengthens the matrix by solid solution in the matrix and increases the hardness of the cast iron, especially the tensile strength.

In addition, when Mo is formed in the pearlite, the pearlite is refined to reduce the section sensitivity of the cylindrical member, which is cast, to improve the mechanical properties of the outer periphery and the mechanical properties of the inner periphery To homogenize the solution.

Further, Mo promotes the precipitation of carbide, and this carbide has an action of improving the sintering resistance.

In order to obtain such an effect, the Mo content is required to be 0.15% or more.

On the other hand, when the content of Mo is too large, the toughness is lowered and the workability is lowered because it becomes too hard.

Therefore, the Mo content is required to be 0.65% or less.

The content of Mo is preferably 0.20% or more and 0.65% or less from the viewpoint of resistance to sintering, and is preferably 0.15% or more and 0.55% or less from the viewpoint of workability.

From the viewpoints of resistance to sintering and workability, it is more preferable to be not less than 0.20% and not more than 0.55%, and most preferably not less than 0.30% and not more than 0.55% from the viewpoint of further improving the tensile strength.

Ni is an element that tightens the base to strengthen the base and promote graphitization (blackening).

In addition, Ni has a function of homogenizing the cross sectional area sensitivity of the cast cylindrical member by making the graphite finely uniform, thereby reducing the difference between the mechanical properties of the outer peripheral portion and the mechanical properties of the inner peripheral portion.

Ni also has an effect of improving Young's modulus.

In order to obtain such an effect, the content of Ni is preferably 0.15% or more.

On the other hand, when the content of Ni is too large, the above effect is saturated as the content of Ni increases, so that the content of Ni is 0.65% or less.

From the viewpoint of improving the Young's modulus, the Ni content is preferably 0.25% or more and 0.65% or less.

As for Mo and Ni, it is preferable that the total content of Mo and Ni is 0.3% or more and 1.30% or less.

By making the total content of Mo and Ni fall within the above range, it becomes extremely easy to improve the tensile strength and the Young's modulus, and at the same time to secure the wear resistance and the resistance to sintering.

In order to improve the tensile strength and the Young's modulus and ensure the processability at the same time, it is preferable that i) the Mo content is 0.30% or more and 0.55% or less, and ii) the total content of Mo and Ni is 0.60% or more and 1.15% desirable.

The remaining parts other than C, Si, Mn, P, S, Cr, Mo, and Ni are Fe and unavoidable impurities.

On the other hand, the structure of the piecemeal graphite cast iron preferably includes at least one kind of matrix selected from the group consisting of pearlite and bainite.

The structure of the cast iron graphite cast iron usually includes graphite and carbide.

The structure of the cast iron graphite cast iron can be appropriately controlled by adjusting the composition within the above range.

The base may contain at least one species selected from the group consisting of pearlite and bainite, and may further contain other phases.

Examples of other phases include ferrite and the like.

When ferrite is contained as a matrix, the area ratio occupied by ferrite is preferably 5% or less.

In addition, it is preferable that the base does not contain a chilled phase (cementite phase).

The crowd consisting of pearlite and bainite may contain (I) pearlite only, (II) both pearlite and bainite, and (III) bainite alone.

Whether the base is the base texture (I) to the base texture (III) can be controlled by the content of Mo and Ni, for example, as shown in Fig.

Fig. 1 is a graph showing the relationship between the content of Mo and Ni and the base texture. In the figure, the abscissa represents the Mo content (%) and the ordinate represents the Ni content (%).

As shown in Fig. 1, a range in which the content of Mo is about 0.25 +/- 0.05% is defined as a boundary (first boundary area B1), and in a region having a small Mo content (first region I) It becomes easy to make the base texture I and conversely, in the region where the Mo content is large (second region II), it becomes easy to make the base texture II.

In the region where the content of Mo is larger than that of the first boundary area (B1), the Mo content is 0.40% or more, the Ni content is in the range of about 0.30 ± 0.05%, the Ni content is 0.35% (Second region (II)) in which the Mo content is small or the content of Ni is large, the range of about 0.45 + 0.05% It becomes easy to make the base structure II into the base structure II. In contrast, in the region where the content of Mo is large and the content of Ni is small (third region III), it becomes easy to make the base structure III.

In the matrix, finely divided graphite is dispersed.

The size of the graphite is not particularly limited, but is, for example, about 4 to 8 (ISO 945-1: 2008).

The area ratio of graphite is not particularly limited, but is usually about 6.0% or more and 17.0% or less, preferably 8.0% or more and 15.0% or less.

The area ratio of graphite can be controlled by the Mo content.

In cast iron cast iron, in the composition containing no Mo, the C component tends to crystallize as graphite or solidify into graphite without forming carbide. However, in the composition containing Mo, the C component contains Mo and P Since the crystallization as graphite is reduced because carbides including the carbides are formed.

The cast iron graphite cast iron includes carbide as described above.

Since the carbide forms the primary sliding surface when the cylindrical member and the counterpart material of the present embodiment are slid, the carbide deteriorates the sliding characteristics even if the graphite structure is finely ground. Can be suppressed.

From the viewpoints of abrasion resistance and resistance to seizure, it is preferable that the areal ratio of the carbide is not less than 0.9% and not more than 5.0% in the continuous region continuous to not less than 0.2 mm in the radial direction (thickness direction) of the cylindrical member.

By setting the area ratio of the carbide to 0.9% or more, it is extremely easy to improve the abrasion resistance and the anti-seizure property as the sliding surfaces contacting with the mating material.

On the other hand, when the area ratio of the carbide is too large, the workability of the cast iron decreases.

Therefore, the area ratio of carbide is preferably 5.0% or less.

The area ratio of the carbide in the continuous region is preferably 1.5% or more and 5.0% or less from the viewpoints of abrasion resistance and resistance to seizure, and 0.9% or more and 4.2% or less from the viewpoint of workability and abrasion resistance, , It is more preferable that it is not less than 1.5% and not more than 4.2%.

In the cylindrical member of the present embodiment, the area ratio of the carbide increases as it goes from the outer circumferential side to the inner circumferential side in the radial direction (thickness direction).

Therefore, the length in the radial direction (thickness direction) of the continuous region can be appropriately selected in a range not exceeding the maximum thickness of the cylindrical member, and the upper limit value of the length in the radial direction is not particularly limited. However, .

Further, the cylindrical member of the present embodiment is manufactured by centrifugal casting using a cylindrical mold (circular cylindrical mold).

Therefore, the outer circumferential surface and the inner circumferential surface of the cylindrical member immediately after casting are formed of a casting surface.

Accordingly, by machining the inner circumferential surface or the outer circumferential surface made of the casting surface by cutting or the like, any one surface selected from the inner circumferential surface and the outer circumferential surface after the processing is formed on one end of the continuous region with respect to the radial direction of the cylindrical member .

When the inner circumferential surface or the outer circumferential surface after the processing, which is formed at one end of the continuous region, is used as a sliding surface for sliding with the mating member, more excellent abrasion resistance and resistance to sintering can be obtained.

The term " edge on one side of the continuous region " means the innermost side of the continuous region when the inner circumferential surface (cast surface) is subjected to processing, and the outermost circumference .

When the inner peripheral surface of the casting surface is processed by cutting or the like and the inner peripheral surface of the inner peripheral surface is formed on the innermost side of the continuous region with respect to the radial direction of the cylindrical member, Can be used as a member that slides with the mating member as a sliding surface.

For example, the cast iron-made cast iron cylindrical member of the present embodiment may be a cylinder liner for an internal combustion engine in which the piston and the piston ring reciprocally slide (reciprocally slide), or a cylinder liner it is particularly preferable that the drum is a brake drum of an internal-type drum brake which is slidable with a brake shoe.

When forming the inner circumferential surface (sliding surface) on the innermost circumferential side of the continuous region, a new outer circumferential surface (machined surface) may also be formed by performing the cutting process or the like on the outer circumferential surface constituted by the cast surface.

For example, in the case where the cylindrical member is inserting into the cylinder block and integrally molded as in the case of Japanese Patent No. 5815262, in order to increase the coupling strength between the cylindrical member and the cylinder block, And the outer circumferential surface of the outer circumferential surface is machined into a complicated shape.

The thickness of the cylindrical member in the case of a complicated outer peripheral surface means a thickness based on a concave portion at the maximum depth of the outer peripheral surface.

In this case, the new outer circumferential surface may be a surface forming the outermost circumferential side of the continuous region, or may be a surface formed in a region further outward than the outermost circumferential side of the continuous region.

When the inner circumferential surface (sliding surface) is formed on the innermost side of the continuous region, the cylindrical member having the outer circumferential surface composed of the inner circumferential surface (sliding surface) and the cast surface is used for the cylinder liner for the internal combustion engine and the brake drum As shown in Fig.

For example, in order to improve the bonding strength with the member (outer peripheral member) provided on the outer peripheral surface of the casting surface so as to cover the outer peripheral side of the cylindrical member, the surface roughness of the casting surface is increased, It is preferable to directly use a cylindrical member having an outer circumferential surface composed of an inner circumferential surface (sliding surface) and a casting surface as a member according to each application.

For example, Japanese Patent No. 3253605 discloses a case where the surface roughness of the casting surface is made large. For example, Japanese Patent No. 4210468, Japanese Patent Laid- 4429025, and the like.

The thickness of the cylindrical shape when the outer peripheral surface is the cast surface and the surface roughness is large refers to the thickness based on the valleys of the surface roughness and the thickness of the cylindrical member when the projections are formed is , And the thickness based on the outer circumferential base surface without the projection.

When the inner circumferential surface (sliding surface) is formed on the innermost circumference side of the continuous region or when the outer circumferential surface (sliding surface) is formed on the outermost circumferential side of the continuous region, the length in the radial direction Is preferably 0.2 mm or more.

This makes it easier to obtain excellent wear resistance and anti-seizure property on the inner circumferential surface or the outer circumferential surface serving as the sliding surface.

If the length in the radial direction of the continuous region is 0.2 mm or more, it can be appropriately selected in accordance with the use of the cylindrical member of the present embodiment within a range that does not exceed the maximum thickness of the finished cylindrical member as a member for each application, More preferably 0.7 mm or more, and more preferably 1.4 mm or more with an increase in the thickness of the film.

The upper limit of the length in the radial direction is not particularly limited, but is preferably 2.7 mm or less in practical use.

Further, when a surface modification treatment (surface modification treatment) such as laser hardening is also performed on the inner circumferential surface (sliding surface) or the outer circumferential surface (sliding surface) newly formed by cutting or the like, Thickness direction) refers to a length measured based on the state before the surface modification treatment is performed.

The cutting of the inner peripheral surface and the outer peripheral surface of the casting surface may be performed only once, or may be performed two or more times.

The length in the radial direction (thickness direction) of the continuous region when the thickness of the cylindrical member immediately after the casting including the casting surface and the outer peripheral surface is set as the reference (100%) is preferably 34% % Or more is more preferable.

In the cylindrical member of the present embodiment, after centrifugal casting, at least the inner circumferential surface (casting surface) is cut for the purpose of eliminating the blowhole.

The processing amount of the cutting process for this purpose can be set to, for example, 1.5 mm to 3.5 mm.

The thickness of the cylindrical member immediately after the centrifugal casting in which the cutting is also performed on the outer peripheral surface (casting surface) is not limited to the thickness of the cylindrical member immediately after the centrifugal casting in which the cutting operation is not performed on the outer peripheral surface Is set to be thicker by the amount of the machining amount required for the cutting process of the casting surface.

The processing amount of the cutting process for this purpose can be set to, for example, 1.5 mm to 3.5 mm.

When the cylindrical member of the present embodiment is used as a cylinder liner having an outer circumferential surface having a casting surface, the outer circumferential surface (cast surface) of the cylindrical member immediately after centrifugal casting using a cylindrical metal mold is set as a reference position (0 mm) (I) a continuous area is formed to include a range of 0.8 mm to 1.2 mm, (ii) a continuous area is formed so as to include a range of 0.8 mm to 1.5 mm, (Iii) a continuous region is formed so as to include a range of 0.8 mm to 2.2 mm, and (iv) a continuous region is formed so as to include a range of 0.8 mm to 3.5 mm, More preferable.

When protrusions having an average height of about 0.1 mm to 2 mm are formed on the outer peripheral surface (casting surface), the outer peripheral base surface (outer peripheral base surface) on which protrusions do not exist is set as the reference position (0 mm).

Here, in the case of forming a new inner peripheral surface (sliding surface) contacting and sliding with the piston ring mounted on the groove (groove) provided on the outer peripheral surface of the piston and the piston, for example, by machining the inner peripheral surface (cast surface) (Sliding surface) in the range of 1.0 mm to 1.2 mm in the case of (i) in the radial direction (thickness direction) of the cylindrical member in order to obtain a sliding surface excellent in abrasion resistance and anti- (Ii), it is preferable to form an inner peripheral surface (sliding surface) within a range of 1.0 mm to 1.5 mm, and in the case of (iii), an inner peripheral surface It is preferable to form an inner peripheral surface (sliding surface) within a range of 1.0 mm to 3.5 mm in the case of (iv).

The area ratio of the carbide in the newly formed inner circumferential surface (sliding surface) or outer circumferential surface (sliding surface) is not limited to the case where the cylindrical member of the present embodiment is used as a cylinder liner, But from the viewpoint of further improvement, it is preferably not less than 2.1% and not more than 5%, and more preferably not less than 3.3% and not more than 5% from the viewpoint of further improving both wear resistance and anti-

The cast iron graphite cast iron cylindrical member according to the second embodiment of the present invention is a cylindrical cast iron cast iron graphite cast iron member,

C: not less than 2.85% but not more than 3.35%, Si: not less than 1.95% nor more than 2.55%, Mn: not less than 0.45% nor more than 0.8%, P: not less than 0.03% nor more than 0.25%, S: not more than 0.15% 0.15 to 0.65% of Cr, 0.15 to 0.55% of Cr, 0.15 to 0.65% of Mo, 0.15 to 0.65% of Ni, and other elements other than C, Si, Mn, P, S, Cr, Mo, Hereinafter referred to as " element X "): more than 0% and not more than 0.6%

And the balance of Fe and inevitable impurities.

The graphite cast iron used in the cast graphite cast iron cylindrical member of the second embodiment of the present invention has an element X exceeding 0% of the composition of the cast graphite cast iron used in the cast graphite cast iron cylindrical member of the first embodiment Graphite cast iron cylindrical member of the first embodiment, except that the content of the graphite cast iron is 0.6% or less.

The cast iron graphite cast iron cylindrical member of the second embodiment of the present invention has excellent mechanical strength and practical workability as well as the cast iron graphite cast iron cylindrical member of the first embodiment and further has excellent abrasion resistance and anti- Excellent.

The element X is an element added for the purpose of further improving and improving specific characteristics among the various characteristics of the cast iron graphite cast iron used in the cast iron graphite cast iron cylindrical member of the first embodiment.

Whether the element X is used as the element X can be appropriately selected in accordance with a specific characteristic for the purpose of improvement and improvement.

It is necessary that the content of the element X exceeds 0% in order to improve or improve specific characteristics.

On the other hand, when the content of the element X is too large, it is difficult to obtain mechanical strength, workability, abrasion resistance, and anti-seizure properties equal to or greater than those of the cast iron graphite cast iron member of the first embodiment.

For this reason, it is necessary that the content of the element X is 0.6% or less.

The content of the element X is preferably 0.03% or more and 0.55% or less.

As the element X, only one kind of element may be used, or two or more kinds of elements may be used.

When two or more kinds of elements are used as the element X, the content of each element can be appropriately selected within a range in which the total content of each element used as the element X is 0.03% or more and 0.6% or less.

As the element X, for example, Cu, B, Ti, V, Nb or the like is preferably used.

Cu is an element effective in stabilizing pearlite by solid-solving the base to strengthen the base.

In addition, Cu increases the hardness of cast iron and prevents whitening, thereby improving corrosion resistance and impact resistance.

In order to obtain such an effect, the content of Cu is preferably 0.05% or more.

On the other hand, the upper limit of the content of Cu may be 0.6% or less, but in order to suppress an increase in the material cost, the practical value is preferably 0.55% or less.

B is an element which precipitates carbide and improves abrasion resistance and anti-seizure property.

In order to obtain such an effect, the content of B is preferably 0.03% or more and 0.15% or less.

Ti is an element that precipitates carbides or promotes graphitization and has an action of finely dividing and uniformly dispersing graphite.

In order to obtain such an effect, the Ti content is preferably 0.03% or more and 0.20% or less.

V has a function of precipitating carbide, suppressing precipitation of graphite, and finely dispersing and uniformly dispersing graphite.

In order to obtain such an effect, the content of V is preferably 0.05% or more and 0.40% or less.

Nb has a function of precipitating carbide.

In order to obtain such an effect, the content of Nb is preferably 0.05% or more and 0.50% or less.

The cast graphite cast iron cylindrical member of the present embodiment can be suitably produced by using a known casting production method.

For example, a molten metal is melted using an electric furnace or the like, and centrifugal casting is performed using a cylindrical metal mold to obtain a cast iron graphite cast iron cylindrical member of the present embodiment having a predetermined dimensional shape, .

 As described above, the cast iron graphite cast iron member of the present embodiment uses the cast iron graphite cast iron having excellent mechanical characteristics, and it is easy to reduce the thickness and to reduce the weight.

Here, the thickness T2 of the cylindrical member can be appropriately selected depending on the use of the cast iron-made cast iron member of the present embodiment, but is preferably 3.5 mm or less, more preferably 1.5 mm or less.

The lower limit of the thickness T2 is preferably 1.0 mm or more in practical use.

The thickness T2 may be achieved only when the cast iron-made cast iron member of the present embodiment is at least used in the final product.

2 (A), the cylinder liner 20A used in the internal combustion engine 10 is the cylinder liner 20A ((20 It is only necessary to be able to realize the above-mentioned thickness T2 in a state where the internal combustion engine is completed (a state used for the final product) such as a state in which the cylinder block 24 is inserting into the cylinder block 24. [

In a state where the cylinder liner 20B (20) before being inserting into the cylinder block 24 shown in Fig. 2B alone, the thickness T1 is smaller than the predetermined thickness A value obtained by adding the machining amount? To the thickness T2 so as to secure the sectional structure, the minimum thickness, etc. For example, it may be thicker than 3.5 mm, or even more than 5.5 mm do.

2 (A) is a perspective view showing the external appearance of the internal combustion engine 10 and is covered with the cylinder block 24 in the cylinder liner 20 shown in Fig. 2 (A) Are shown by dotted lines.

A typical dimension of the cylinder liner 20 as shown in Fig. 2 is about 50 mm to 180 mm in outer diameter and about 70 mm to 270 mm in length.

The hardness, tensile strength and Young's modulus of the cast graphite cast iron used in the cast iron graphite cast iron cylindrical member of the present embodiment are not particularly limited. However, the hardness is preferably 102 HRB or more and 112 HRB or less, and the tensile strength is 300 MPa Or more, and the Young's modulus is preferably 110 GPa or more, and it is more preferable that the three numerical ranges are simultaneously satisfied.

The tensile strength is preferably 330 MPa or more, more preferably 350 MPa or more, and the Young's modulus is preferably 120 GPa or more.

The application of the cast iron-graphite cast iron member of the present embodiment is not particularly limited, but it is particularly suitable to use it as a cylinder liner used for an internal combustion engine in which the piston and the piston ring reciprocally slide.

The cylinder liner is used in an internal combustion engine and is used as a dry cylinder liner fitting into a cylinder block of a cast iron or a cylinder liner inserting into a cylinder block made of an aluminum alloy or the like .

A piston ring mounted on a groove provided on the outer peripheral surface of the piston and the piston slides the inner peripheral surface of the cylinder liner.

For this reason, the cylinder liner is required to have excellent abrasion resistance and resistance to sintering.

In recent years, the pitch between the cylinder bores is also reduced in order to reduce the weight of the cylinder block, particularly for the purpose of improving the fuel economy of the automobile (fuel economy improvement).

For this reason, a cooling method for lowering the temperature of the inner wall surface of the cylinder bore at the time of combustion is an issue.

On the other hand, if the thickness T2 of the cylinder liner 20A placed in the internal combustion engine 10 can be made thinner as shown in Fig. 2A, the two cylinder bores (More precisely, between the outer circumferential surfaces of the two cylinder liners 20A) of the cooling fluid passage 26 can be made larger.

In this case, it is easy to further increase the cooling efficiency of the cylinder bore 22.

On the other hand, the cast graphite cast iron cylindrical member of the present embodiment is not only excellent in wear resistance and resistance to seizure but also has excellent mechanical strength, so that it is extremely easy to reduce the thickness T2 of the cylinder liner 20A.

Therefore, the cast iron-made cast iron cylindrical member of the present embodiment can sufficiently cope with the above-mentioned demands.

In addition, by thinning the thickness T2, the weight reduction and volume reduction of the cylinder liner 20A can be facilitated.

For example, assuming that the thickness T2 is 2.2 mm, the outer diameter is 85 mm, the inner diameter is 80.6 mm and the axial length is 136 mm, if the thickness T2 is 1.5 mm, the volume is 77.8 cm ³ To 53.5 cm < ^{3 &} gt ;, and the weight is reduced by 176.2 g from 564.1 g to 387.9 g.

Here, the weight calculation was carried out by setting the specific gravity of the piecemeal graphite cast iron to 7.25 g / cm < ³ >.

The cast graphite cast iron cylindrical member of the present embodiment is also very suitable for use as a brake drum of an internal-contact type drum brake which slides on a brake shoe on the inner circumferential surface.

3 is a schematic cross-sectional view showing an example of an internal-type drum brake using the cast iron-made cast iron cylindrical member of the present embodiment as a brake drum, and is a plane including a rotating shaft of a wheel Sectional view when the wheel is cut is shown.

3, an inner peripheral surface 32S of a substantially cylindrical drum portion 32 constituting a part of a wheel 30 having a center line L as a rotation axis is provided with a brake drum 34 A cast iron-made cylindrical member) is mounted by inserting.

A brake shoe 36 is disposed on the inner peripheral surface 34S side of the brake drum 34. [

The brake shoe 36 slides in contact with the inner circumferential surface 34S of the brake drum 34 during the braking operation.

In addition, the brake drum of the internal-type drum brake is required to have abrasion resistance, anti-seizure resistance, and thermal conductivity.

On the other hand, the cast iron-made cast iron cylindrical member of the present embodiment is not only excellent in wear resistance and resistance to seizure but also excellent in mechanical strength, so that the thickness of the brake drum 34 can be reduced.

The thinning of the brake drum 34 can consequently improve the thermal conductivity.

Example

Hereinafter, the cast graphite cast iron cylindrical member of the present invention will be described by way of examples, but the present invention is not limited to the following examples.

1. Manufacturing of cylindrical members

(Outer diameter: 85 mm, inner diameter: 74 mm (thickness: 5.5 mm), axial length: 136 mm) was produced by centrifugal casting.

Further, at the time of centrifugal casting, a molten metal was poured into a cylindrical member after a coating material (coating material) having a thickness of 1 mm was coated (coated) on the inner peripheral surface of the cylindrical metal mold.

Further, the drawing member attached to the outer peripheral surface (casting surface) of the cylindrical member taken out from the cylindrical mold was removed by shot blast.

The surface roughness of the outer peripheral surface of the cylindrical member thus obtained was 160 탆 at the maximum height Ry.

2. Preparation of various test specimens

Four rod-like members (length (a): 136 mm, width (b): 15) from the positions of 0 °, 90 °, 180 ° and 270 ° with respect to the circumferential direction of the cylindrical members of the respective Examples and Comparative Examples mm and thickness (c): 5.5 mm) were cut out, and the cylindrical member was divided into four pieces in the circumferential direction to obtain four arcuate columnar members (arc-shaped columnar members).

The length (a), the width (b), and the thickness (c) of the member or the test piece cut out from the cylindrical member are respectively the length in the axial direction of the cylindrical member, the length in the circumferential direction, Thickness direction).

Next, a first test piece (length (a): 25 mm, width (b): 15 mm, thickness (c): 5.5 mm) was cut from the central portion in the longitudinal direction (longitudinal direction) of each bar- I got it.

Two members (length (a): 40 mm, width (b): 15 mm, thickness (c): 5.5 mm) were cut out from both sides of the central portion in the longitudinal direction of the stick- And a second test piece for composition analysis was used.

As a result, four first test pieces and four second test pieces were prepared from one cylindrical member.

A third test piece (outline shape: length (a): 120 mm, outer diameter: 4 mm) and a fourth test piece for Young's modulus test (outline shape: (Length (a): 120 mm, outer diameter 4 mm), a fifth test piece (length (a): 70 mm, width (b): 10 mm, thickness (c): 5.5 mm) A sixth test piece for testing (length (a): 70 mm, width (b): 10 mm, thickness (c): 5.5 mm) was cut out.

As a result, four third test pieces to sixth test pieces were prepared from one cylindrical member.

The details of the third test piece and the fourth test piece will be described later.

3. Various evaluation of cylindrical members

The graphite area ratio, the carbide area ratio, the base structure, the hardness, the tensile strength, the Young's modulus, the resistance to seizure, the abrasion resistance, and the workability were evaluated for the cylindrical members of each of the examples and comparative examples shown in Table 1. The results are shown in Tables 1 to 5.

The graphite cast iron used for the cylindrical member of Comparative Example 1 shown in Tables 1 to 5 is the same as the constituent material of the cylinder liner used in the internal combustion engine of a commercial vehicle.

Details of evaluation methods of various evaluation items in Tables 1 to 5 are as follows.

(1) Composition

Table 1 shows the results of analysis of the composition of the obtained cylindrical member by Photoelectric Emission Spectroscopic Analysis (PDA-7020, manufactured by Shimadzu Corporation, Japan) based on JIS 2611-1977 .

The composition analysis was carried out by using a sample for measurement in which the second test piece was completely dissolved and formed into a predetermined shape.

The results shown in Table 1 are obtained by averaging the respective measured values of the four second test pieces.

(2) Graphite area ratio

The cut sections (length (a): 25 mm, thickness (c): 5.5 mm) of the first test pieces of each of the examples and comparative examples were polished.

Subsequently, photographs were taken at positions 0.8 mm, 1.5 mm, 2.2 mm, and 3.5 mm from the outer peripheral surface side of the cylindrical member in the polished surface by a metallurgical microscope (magnification: 400 times).

Next, the obtained photograph was subjected to binarization processing (gray scale), and image analysis (image analysis) was performed to obtain the graphite area ratio (%). The results are shown in Table 2.

The graphite area percentages (%) shown in Table 2 are values obtained by averaging the measured values of the four first test pieces.

For reference, FIG. 4 shows a metallographic micrograph (magnification: 400 times) of Example 11.

As shown in Fig. 4, flake-shaped graphite (black flank portion in the middle) was observed.

The same piece graphite was also observed in all other examples and comparative examples.

(3) Carbide area ratio

The grinding surface (length (a): 25 mm, thickness (c): 5.5 mm) of the first test piece used for measuring the graphite areal ratio was again polished and etched with a corrosive liquid (10% ).

Subsequently, photographs were taken at positions 0.8 mm, 1.5 mm, 2.2 mm and 3.5 mm from the outer circumferential surface side of the cylindrical member in the etched surface by a metallurgical microscope (magnification: 400 times).

Next, the obtained photograph was binarized (gray-scaled) and image-analyzed to obtain the carbide area ratio (%). The results are shown in Table 2.

In addition, the carbide area ratio (%) shown in Table 2 is a value obtained by averaging the measured values of four first test pieces.

For reference, FIG. 5 shows an image (magnification: 400 times) after gray scale used for determining the carbide area ratio of Example 11.

As shown in Fig. 5, the white portion is a carbide.

The same carbides were also observed in all other examples and comparative examples.

(4) base organization

The etching surface (length (a): 25 mm, thickness (c): 5.5 mm) of the first test piece used for measuring the carbide area ratio was again polished and etched with a corrosive liquid (3% picral solution) After that, whether or not pearlite and bainite were contained at positions 0.8 mm, 1.5 mm, 2.2 mm and 3.5 mm from the outer peripheral surface side of the cylindrical member was visually judged by a metallurgical microscope did. The results are shown in Table 2.

In Table 2, "P" means that pearlite was observed, "B" means that bainite was observed, and "P + B" means that both pearlite and bainite were observed .

In addition, as shown in the photograph of the metallographic microscope shown in Fig. 4, during the observation of the metallographic microscope, the bainite is observed as a white part, and the pearlite is observed as a gray part.

(5) Hardness

The hardness was measured at a position of 2.0 mm from the outer circumferential surface side of the cylindrical member in the cut section (length (a): 25 mm, thickness (c): 5.5 mm) of the first test piece.

Here, the hardness was measured in accordance with JIS Z 2245. The results are shown in Table 3.

The hardness shown in Table 3 is a value obtained by averaging measurement values of four first test pieces.

(6) Tensile strength and Young's modulus

As the third test piece and the fourth test piece used for measuring the tensile strength and the Young's modulus, a stick-shaped test piece 40 shown in Fig. 6 was used.

The bar-shaped test piece 40 has a length L1 of 120 mm and both end portions 42 in the axial direction C are cylindrical portions having a diameter D of 4 mm. Is a circumferential portion having a diameter d of 3 mm.

The chamfered portion 44R is chamfered at both ends of the central portion 44 to form a central portion 44 excluding chamfered portions 44R. ) Is 40 mm.

The tensile strength and Young's modulus were measured in accordance with JIS Z 2241 and JIS Z 2280, respectively.

Specifically, the bar-shaped test piece 40 is set on a tensile tester (type AG-5000E, manufactured by Shimadzu Corporation, Japan) and measured at a tensile speed of 0.3 mm / min did. The results are shown in Table 3.

The tensile strength and Young's modulus shown in Table 3 are values obtained by averaging the measured values of four test pieces.

In this test, a cylindrical member having an axial length of 136 mm was used. However, if a cylindrical member having an axial length of 120 mm or less is used, the length L1 is 50 mm and the length L2 is The tensile strength and Young's modulus are evaluated using a bar-shaped test piece (40) of 20 mm.

(7) Seizure resistance

The sintering resistance was evaluated by using a ring-on-plate type reciprocating friction tester shown in Fig.

One lower test piece (lower test piece) 50 was taken from one fifth test piece.

Here, for each lower test piece 50, the test was first performed at a position of 3.5 mm from the outer peripheral surface side of the cylindrical member, and then the test was performed at a position of 2.2 mm.

Here, the evaluation of the resistance to sticking was carried out in the following order.

First, a spindle oil is applied to a surface 50S of a flat plate-like lower test piece 50 and then a pin-shaped upper test piece 52 is applied with a load P by a spring. (Hemispherical tip portion) 52E of the lower test piece 50 is pressed against the surface 50S of the lower test piece 50.

In this state, the lower test piece 50 was reciprocated in the direction orthogonal to the application direction (load direction) of the load P.

The load P is increased by a constant value every time a predetermined period of time is elapsed while sliding the front end portion 52E of the hemispherical upper surface of the upper test piece 52 and the surface 50S of the lower test piece 50, A load (P) (a squeeze load) in which a scuff (scuff) is generated in the surface 50S of the test piece 50 was measured.

The test conditions are as follows.

(a) Upper test piece 52

· Material: JIS SUS420J2 material

· Hemispherical tip (52E) Coating of surface (sliding surface): Hard chrome plating

· Finishing process of the hemispherical tip (52E) surface (sliding surface): Mirror surface machining (mirror surface machining)

· Increase rate of load (P): 20 N for 1 minute and 20 N for 1 minute

(b) Lower test piece 50

Samples: A surface corresponding to the outer circumferential surface and the inner circumferential surface of the cylindrical member in the fifth test piece (length (a): 70 mm, width (b): 10 mm, thickness (c): 5.5 mm) A plate-like member

Finishing of the surface 50S (sliding surface): Mirror surface machining (In addition, the test is performed after the first test is performed by forming the surface 50S (sliding surface) at a position 3.5 mm from the outer circumferential surface, And a second test was carried out by forming a surface 50S (sliding surface) at a position of 2.2 mm from the outer peripheral surface.

· Movement speed: 100 round trips per minute

· Travel distance of one round trip: 100 mm

The results are shown in Table 4.

Here, the external load used in the calculation of the " external load ratio (load ratio) " shown in Table 4 is a value obtained by averaging measured values of four test pieces at the same position in the radial direction of the cylindrical member.

In Table 4, the " slack load ratio " is a relative value of the slack load when the slack load of Comparative Example 1 is taken as the reference value (100).

In addition, the evaluation criteria of " the evaluation of the internal adhesiveness " shown in Table 4 are as follows.

- Evaluation Criteria of "Seizure Resistance Evaluation"

A: Adherence load ratio is over 150.

B: Sealed load ratio is more than 120 and less than 150.

C: Sealed load ratio is 100 or more and less than 120.

(8) Abrasion resistance

The wear resistance was evaluated using a ring-on-plate type reciprocating friction tester shown in Fig.

One lower test piece 50 was taken from one fifth test piece.

Here, for each lower test piece 50, the test was first performed at a position of 3.5 mm from the outer peripheral surface side of the cylindrical member, and then the test was performed at a position of 2.2 mm.

Here, the abrasion resistance was evaluated in the following order.

First, the hemispherical tip 52E of the pin-shaped upper test piece 52 is pressed against the surface 50S of the flat lower test piece 50 with a load P by a spring.

In this state, the lower test piece 50 was reciprocated in the direction orthogonal to the application direction of the load P.

During the test, a spindle oil is spun between the surface 50S of the lower test piece 50 and the hemispherical tip 52E of the upper test piece 52 by using a tubing pump or an air dispenser. oil was continuously added dropwise.

The reciprocating motion was stopped after a lapse of a predetermined time, and the depth of wear of the surface 50S of the lower test piece 50 was measured by a surface roughness meter.

The test conditions are as follows.

(a) Upper test piece 52

· Material: JIS SUS420J2 material

Coating of the hemispherical tip 52E surface (sliding surface): CrN film (film formation by PVD (Physical Vapor Deposition) method)

· Finishing process of the hemispherical tip (52E) surface (sliding surface): Mirror surface machining

· Load (P): 100 N

(b) Lower test piece 50

Sample: A surface corresponding to the outer circumferential surface and the inner circumferential surface of the cylindrical member in the sixth test piece (length (a): 70 mm, width (b): 10 mm, thickness (c): 5.5 mm) A plate-like member

Finishing of surface 50S (sliding surface): Mirror surface machining (In addition, the test is performed after the first test is performed by forming the surface 50S (sliding surface) at a position 3.5 mm from the outer circumferential surface, And a second test was carried out by forming a surface 50S (sliding surface) at a position of 2.2 mm from the outer peripheral surface.

· Movement speed: 600 round trips per minute

· Travel distance of one round trip: 100 mm

(c) Test time: 60 minutes

The results are shown in Table 4.

Here, the wear depth used for calculation of the " wear rate ratio " shown in Table 4 is a value obtained by averaging the measured values of four test pieces with respect to the same position in the radial direction of the cylindrical member.

The " wear amount ratio " shown in Table 4 is a relative value of the wear amount when the wear amount of the comparative example 1 is taken as the reference value (100).

The evaluation criteria of " wear resistance evaluation " shown in Table 4 are as follows.

- Evaluation Criteria of "Abrasion Resistance Evaluation"

A: wear ratio less than 10.

B: Wear rate is over 10 but not more than 50.

C: Wear rate is over 50 and not more than 100.

(9) Processability

The processability was evaluated in the following order.

For the evaluation, four cylindrical members were used for each of the examples and comparative examples, and the following cutting test was carried out four times.

First, a machining center in which a cutter rotates was used, and the inner circumferential surface (casting surface) of the cylindrical member of each of the examples and the comparative examples was subjected to rough processing until the thickness became 2.2 mm, I completely removed the address (鑄 巢).

Next, the rough inner circumferential surface was processed to a thickness of 1.4 mm using a new cutter (material type: CBN, throw away chip, nose radius (R): 0.8 mm) , And the maximum wear width of the cut on the flank face after cutting was measured.

The cutting condition at this time was a cutting length of 136 mm, a cutting depth of 0.05 mm, a cutting speed of 0.35 mm / rev, and a cut rotation speed of 3000 rpm.

The results are shown in Table 5.

The maximum wear width used in the calculation of the " cut abrasion ratio " shown in Table 5 is a value obtained by averaging the measured values of the four cutting tests.

In Table 5, the " cut wear ratio " is a relative value of the maximum wear width when the maximum wear width of Comparative Example 4 is taken as the reference value (100).

The evaluation criteria of " workability evaluation " in Table 5 are as follows.

- Evaluation Criteria for "Processability Evaluation"

A: The cut wear ratio is less than 80

B: The cut wear ratio is 80 or more and less than 90

C: Wear rate of the cut is 90 or more and 100 or less

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

In the case where the cylindrical members of Examples 1 to 21 are used as a cylinder liner having an outer circumferential surface composed of a casting surface, for example, only the inner circumferential surface (casting surface) of the cylindrical member after centrifugal casting is cut, Can be formed within a range of 1.0 mm to 2.0 mm from a new inner circumferential surface (a sliding surface contacting and sliding with a piston ring mounted on a groove provided on the outer circumferential surface of the piston and the piston).

Further, at the time of cutting the inner peripheral surface (cast surface), the machining amount by cutting is set to 2 mm for the purpose of completely removing the address.

Thereafter, the inner peripheral surface (cast surface) can be formed at a position where the distance from the outer peripheral surface (cast surface) is within the above-mentioned range by further performing cutting processing or the like.

In this case, the area ratio of the carbide in the new inner peripheral surface (cast surface) is in the range of 0.9% or more and 5.0% or less in any of the examples.

10: Internal combustion engine
20, 20A, 20B: Cylinder liners (cast graphite cast iron member)
22: cylinder bore
24: Cylinder block
26: flow path for cooling liquid
30: Wheel
32:
32S: inner peripheral surface
34: Brake drum (cast iron graphite cast iron cylinder member)
34S: inner peripheral surface
36: Brake Shoe
40: stick-shaped test piece
42: Both end portions
44: central portion
44R: chamfering part
50: Lower test piece
50S: Surface
52: upper test piece
52E: hemispherical tip

Claims (13)

A cast member made of cast iron graphite cast iron,
Wherein the flaky graphite cast iron has a weight percent,
C: not less than 2.85% but not more than 3.35%, Si: not less than 1.95% and not more than 2.55%, Mn: not less than 0.45% and not more than 0.8%, P: not less than 0.03% and not more than 0.25%, S: not more than 0.15%, Cr: , Mo: not less than 0.15% and not more than 0.65%, Ni: not less than 0.15% and not more than 0.65%
The balance being Fe and inevitable impurities,
Casted graphite cast iron member. A cast member made of cast iron graphite cast iron,
Wherein the flaky graphite cast iron has a weight percent,
C: not less than 2.85% but not more than 3.35%, Si: not less than 1.95% and not more than 2.55%, Mn: not less than 0.45% and not more than 0.8%, P: not less than 0.03% and not more than 0.25%, S: not more than 0.15%, Cr: 0.15% or more and 0.65% or less of Mo, 0.15% or more and 0.65% or less of Ni and 0.05% or more and 0.55% or less of Cu,
And the balance of Fe and inevitable impurities.
Casted graphite cast iron member. 3. The method according to claim 1 or 2,
Wherein the cast graphite cast iron has a structure containing at least one matrix selected from the group consisting of pearlite and bainite. 3. The method according to claim 1 or 2,
Wherein the content of Mo in the cast graphite cast iron is 0.20% or more and 0.55% or less by mass percent. 3. The method according to claim 1 or 2,
Graphite cast iron cylindrical member having a composition of i) the content of Mo in the cast graphite cast iron is 0.30% or more and 0.55% or less, and ii) the total content of Mo and Ni in the cast graphite cast iron is 0.60% . 3. The method according to claim 1 or 2,
Wherein the thickness of the cylindrical member is 1.0 mm or more and 3.5 mm or less. 3. The method according to claim 1 or 2,
Graphite cast iron cylindrical member having a hardness of 102 HRB or more and 112 HRB or less, a tensile strength of 300 MPa or more, and a Young's modulus of 110 GPa or more. 3. The method according to claim 1 or 2,
Wherein the casting graphite cast iron includes a carbide, and the area ratio of the carbide is not less than 0.9% and not more than 5.0% in a continuous region continuous to not less than 0.2 mm with respect to the diameter direction of the cylindrical member. 9. The method of claim 8,
Wherein the length of the continuous region in the radial direction of the cylindrical member is 2.7 mm or less. 9. The method of claim 8,
Wherein one surface selected from the inner circumferential surface and the outer circumferential surface of the cylindrical member is formed at one end of the continuous region with respect to the radial direction of the cylindrical member. 11. The method of claim 10,
Wherein the inner peripheral surface is a cylinder liner for an internal combustion engine in which the piston and the piston ring are reciprocally slid while the inner peripheral surface is formed on the innermost side of the continuous region with respect to the radial direction of the cylindrical member. 11. The method of claim 10,
Wherein the inner peripheral surface is a brake drum of an internal-type drum brake which is formed on the innermost side of the continuous region with respect to the radial direction of the cylindrical member and slidably engages with the brake shoes on the inner peripheral surface. delete

Images